B2 B3 Forged Steel Ball for Primary Grinding of Hard-Rock Magnetite and Hematite

Product Description

B2 B3 Forged Steel Ball for Primary Grinding of Hard-Rock Magnetite and Hematite
Update:September 11th, 2026

Junda B2 and B3 heavy-duty forged steel grinding balls are engineered for primary grinding of hard-rock iron ores, including magnetite, hematite, and mixed iron ore deposits. Produced from high-alloy steel through controlled hot forging and heat treatment, they deliver surface hardness of 59-66 HRC, volume (core) hardness maintained throughout the ball cross-section, impact toughness ≥12 J/cm², and a crushing rate far less than 1%.

Key specifications:

• Material grades: B2 (high-carbon Cr-alloy) and B3 (Si-Mn-Cr alloy)
• Available diameters: Φ20-125mm (custom to Φ150mm on request)
• Surface hardness: 61-66 HRC (B2) / 59-63 HRC (B3, diameter-dependent)
• Volume hardness: 60-66 HRC (B2 small) through 53-60 HRC (B3 large)
• Impact toughness: ≥12 J/cm² (product specification)
• Crushing rate: far less than 1% (product specification)
• Applications: primary ball mills, SAG mill downstream ball mills, magnetite and hematite iron ore grinding circuits
• Certifications: ISO 9001, ISO 45001, ISO 14001, CE

1. Why B2 / B3 for Magnetite and Hematite Primary Grinding

Magnetite (Mohs hardness ~5.5-6.5) and hematite (Mohs ~5-6) primary grinding circuits impose the most severe demands on grinding media: coarse, hard feed particles; high mill loading; continuous high-energy impact. Standard carbon-manganese grades (60Mn, 65Mn) achieve 57-62 HRC surface hardness and are suited to cement and coal grinding. For hard-rock iron ore primary grinding, B2 and B3 high-alloy grades deliver the higher hardness, toughness, and structural integrity required.
 

Performance Factor	B2 / B3 Value	Why It Matters in Primary Grinding
High surface hardness	B2: 61-66 HRC B3: 59-63 HRC	Hard-rock ore abrasion demands hardness above 59 HRC. Higher surface hardness directly reduces wear rate and media consumption per tonne of ore processed.
High volume hardness	B2: 60-66 HRC (small-medium) B3: 53-62 HRC (medium-large)	Core hardness retention ensures structural integrity as the ball wears, preventing sudden fracture at reduced diameter during continuous primary grinding.
Low crushing rate	Far less than 1% (product specification)	Ball breakage in primary grinding is directly costly: fragments damage mill liners, contaminate ore pulp, and require emergency media top-up.
High impact toughness	≥12 J/cm² (product specification)	Primary grinding involves high-energy impact from coarse, hard feed particles. Toughness prevents cracking even under peak impact conditions.
High-alloy composition	B2: Cr 0.2-0.6% B3: Cr 0.7-1.20%, Si 1.2-2.00%	Chromium and silicon additions refine microstructure, improve hardenability depth, and increase wear-resistance potential beyond standard Mn-steel grades.

2. Grade Comparison: B2 vs. B3

Feature	B2	B3
Carbon (C%)	0.72-1.03	0.53-0.88
Silicon (Si%)	0.15-0.35	1.2-2.00
Manganese (Mn%)	0.3-1.2	0.50-1.20
Chromium (Cr%)	0.2-0.6	0.7-1.20
Ni%	≤0.25	≤0.25
P% / S%	≤0.035 / ≤0.035	≤0.035 / ≤0.035
Surface hardness	61-66 HRC	59-63 HRC
Volume hardness	60-66 HRC	53-62 HRC
Typical diameter range	Φ20-65mm	Φ65-125mm
Primary advantage	Maximum hardness, small-medium balls	Toughness + hardness balance, large balls

3. Technical Parameters

All values sourced directly from the JUNDA product specification page (fetched Sep 2026). Final acceptance values confirmed against the batch inspection report issued with each shipment.
Dimensional and hardness parameters - B2 / B3 | Φ20-125mm:
 

Inch	Size	Weight (kg)	Tolerance (mm)	Grade	Surface HRC	Volume HRC
3/4"	D20mm	0.037 ± 0.005	2 ± 1	B2	63-66	63-66
1"	D25mm	0.072 ± 0.010	2 ± 1	B2	63-66	63-66
1-1/4"	D30mm	0.130 ± 0.020	2 ± 1	B2	63-66	63-66
1-1/2"	D40mm	0.300 ± 0.040	2 ± 1	B2	62-66	62-66
2"	D50mm	0.600 ± 0.050	2 ± 1	B2	62-65	61-64
2-1/2"	D60mm	1.000 ± 0.050	2 ± 1.5	B2	62-65	60-62
2-1/2" (B2)	D65mm	1.300 ± 0.050	2 ± 1.5	B2	61-64	60-62
2-1/2" (B3)	D65mm	1.300 ± 0.050	2 ± 1.5	B3	61-63	60-62
3"	D75mm	2.000 ± 0.060	3 ± 2	B3	61-63	60-62
3" (Hot rolled)	D80mm	2.000 ± 0.060	3 ± 2	B3	60-63	60-62
3" (Forged)	D80mm	2.100 ± 0.060	3 ± 2	B3	60-62	53-57
3-1/2"	D90mm	3.000 ± 0.070	3 ± 2	B3	60-63	59-62
4"	D100mm	4.100 ± 0.150	3 ± 2	B3	60-63	59-62
4-1/2"	D115mm	6.300 ± 0.150	3 ± 2	B3	60-63	57-60
5"	D125mm	8.100 ± 0.300	3 ± 2	B3	59-62	55-60

4. Application Guide

Magnetite Iron Ore Primary Grinding

Magnetite (Fe₃O₄) primary grinding circuits process some of the hardest and most abrasive iron ore types. B2 and B3 forged steel balls are selected for magnetite primary grinding circuits to deliver low media consumption, minimal ball breakage, and sustained grinding efficiency over long operating campaigns.

• Magnetite primary ball mills
• SAG mill downstream ball mills (SABC circuits)
• Magnetite ore concentrators (iron ore beneficiation plants)
• Wet and dry primary grinding of magnetite
• High-intensity continuous grinding circuits

Hematite Iron Ore Primary Grinding

Hematite (Fe₂O₃) primary grinding typically involves large feed sizes and sustained abrasive-plus-impact wear conditions. B3 large balls (Φ75-125mm) are particularly suited to first-stage hematite primary grinding where coarse feed requires high-energy impact capability.

• Hematite primary ball mills
• Direct-reduction iron ore grinding circuits
• Hematite beneficiation plant primary grinding stages
• Mixed magnetite-hematite ore processing plants

Other Hard-Rock Mining Applications

• Hard-rock gold ore primary grinding
• Copper ore (porphyry type) primary ball mills
• Lead-zinc ore coarse grinding
• Bauxite and aluminum ore primary grinding
• Industrial mineral processing primary grinding circuits

Every B2/B3 forged steel grinding ball is inspected before shipment: surface hardness (59-66 HRC) and volume hardness (53-66 HRC) by Rockwell tester, chemical composition by spectrometer, diameter tolerance within ±1-2mm, and visual check for cracks and shape. Impact toughness is confirmed at ≥12 J/cm² and crushing rate at far less than 1%. A batch test report is issued with every order.

Company Profile

Established in 2005, Jinan Junda Industrial Technology Co., Ltd. is a manufacturer and exporter of forged steel balls, cast steel balls, steel rods, and surface treatment abrasives. Our grinding media range covers standard grades (60Mn, 65Mn) through high-alloy grades (B2, B3, B6) for the full spectrum from cement and coal grinding to hard-rock mining primary grinding.

• 20+ years of manufacturing experience (established 2005)
• Exported to 100+ countries including USA, Canada, Chile, Peru, Australia, Germany, UK, Japan, South Africa, Malaysia
• ISO 9001 / CE (applicable products) / KOC certified; BV audited factory
• Diameter range Φ20-150mm; custom specifications accepted
• OEM, custom grade, and custom packing orders welcome

FAQ

Q1: What is the minimum order quantity?
 A: Please confirm with our sales team. Mixed sizes and grades in one order are accepted. Custom sizes to Φ150mm available.

Q2: What is the delivery lead time? 
A: 5-10 working days after payment, subject to order quantity and production schedule.

Q3: What payment methods are accepted?
 A: T/T, L/C, Western Union, MoneyGram.

Q4: What documentation comes with each shipment?
 A: Batch inspection report (hardness, composition, dimensions) + certificate of conformance. Third-party inspection available on request.

Q5: Can sizes, grades, or hardness be customized?
 A: Yes. Provide your technical specification and quantity to confirm feasibility.

Q6: Do you supply both mining-grade and cement/coal-grade balls? 
A: Yes. Full range: 60Mn / 65Mn for cement and coal grinding; B2 / B3 for hard-rock mining; B6 for extreme wear conditions. Multiple grades per order accepted.